I have never done anything like this before but would like to pass on what \i think is good news regarding Wiper Blades. I required a new set for my C4a nd was horrified at the cost I dont know what a dealer charges for factory parts but Valeo were quoted to me at over £50, not only that but the Motor Factor didnt have stock and none were available till 3rd week in October. So I looked online, I found a number of people offering sets but on closer inspection they did not have the correct fitting for a 2006 model they have the 'underclip' fitting. Then found a pair with the correct fitting at approx £26 including postage, they arrived in 2 days comunication with the seller was great and I cannot recommend him enough. He trades under the name of 'singlewiper' or if you search for C4 wiperblades and scrole through them you will find him. Hope others find this helpful